Why do I get a 400 error when visiting a website?
If you see the error message, "400 Error. Bad Request," don't worry — it's not your fault. Bad requests are typically caused by a misconfiguration on the web server. It may be a syntax error in the PHP code of a page, an improper redirect in an .HTACCESS file, or an issue with the server itself. A 400 error may also get displayed if a server is overwhelmed with requests and cannot process new ones.
In summary, a 400 error is a general error message that is displayed when the server cannot process a request. If you see this error on a site you visit often, the issue will most likely be fixed and the error message will go away if you visit website later in the day. If not, you can email the webmaster and notify him of the error so he can fix it.